I was going to do intense research and write a tutorial, but doing a bit of research I found nice articles that would pretty much cover what I would write, so instead of writing a tutorial, I'll drop a bunch of links that has a lot of information about it.
Some things I learned, is that you cannot have a secure setup if you distribute the password with your shit, there is no fool-proof way to hide it, only mere obfuscation... sadly.
If my programs have to communicate with web/DB, I always make a PHP backend/API to which I send appropriate commands and get the output instead of just connecting straight to the DB or sending raw SQL commands even to the backend...
security through obscurity is the only way to go :-/
Here are the links:
A discussion about theoretical string hiding:
http://stackoverflow.com/questions/1356896/how-to-hide-a-string-in-binary-code
Some tutorial-ish writeup with C code:
http://create.stephan-brumme.com/hide-strings-executable/
The most informative article from MS, however includes lots of WinAPI, probably not recommended for Linuxfags:
http://msdn.microsoft.com/en-us/magazine/cc164054.aspx
Some example code:
http://etutorials.org/Programming/secure+programming/Chapter+12.+Anti-Tampering/12.11+Hiding+Strings/
Another informative article, probably the best one, however only with C++ code:
http://www.codeproject.com/Articles/502283/Strings-Obfuscation-System
If anyone has their own methods or at least ideas to discuss to go about hiding strings in code, please share